The present invention, relates to plastic bags and more particularly, to a roll of plastic bags wherein the bags are partially opened as they are dispensed.
In a supermarket or food market, fresh produce is often displayed in bulk, frequently in piles of loose items. Consumers must take a bag from a nearby source, and then select and bag their own fruits and vegetables. Typically, the source of bags is a vertically or horizontally positioned cylindrical roll of flattened multi-ply plastic film bags supplied in continuous strips.
One type of bag used in a roll is the PULL-N-PAK(copyright) bag. This comprises a flat tube of plastic material in which the bags are fully gussetted on each side and folded lengthwise to form a star-sealed eight-ply configuration. The bags have a weld for the bag bottom and there is a separation line of perforations adjacent the weld of each bag. The separation line comprises multiple perforations extending through all eight layers of the bag. A slot is placed in the center of the separation line and extends through all of the layers.
The roll of bags is placed in a dispenser, for example, of the type shown in U.S. Pat. No. 5,558,262. The user pulls the first bag over a tongue of the dispenser which engages the slot in the separation line. The front of the next bag is trapped in the gap between the tongue and a finger behind the tongue and is held in the gap. Continued pulling of the first bag produces a force which separates the first bag from the next bag remaining on the roll at the separation line.
A problem with bags provided on a continuous strip is that the user often finds it difficult to open the bag once it has been removed from the strip. The user may even find it difficult to determine which end of the removed bag is the end that opens. The slick finish of the thin film walls of the bag, the static adhesion of thin plastic films and the perforation forces applied to the films in order to provide the separation lines may cause the plies at the opening of the bag to resist separation in which case a user may need two hands to open the bag. This can be a nuisance when the consumer has already selected and is holding items to be placed in the bag.
An object of the present invention is to provide plastic bags which, when supplied in continuous strips, are more easily opened than previous bags.
A further object is to provide a produce bag which is dispensed to the user in a partially opened state.
A further object of the invention is to provide a continuous strip of produce bags on a roll such that removing a leading bag from the roll readily identifies the opening end of an adjacent successive bag on the roll.
An additional object of the invention is to provide a method and apparatus for processing a moving web of multi-ply bags to separate one layer of each bag along a separation line to provide a roll of plastic bags which are easily opened after separation from the roll.
According to the invention, a roll of plastic bags, having multiple layers, includes at least one outer layer detached at the separation line from the adjacent bags.
In a preferred embodiment of the invention, the bags are provided in the form of a web which is folded so that one longitudinal edge is a fold line. Adjacent bags are separated by a weld and a separation line. An outer layer of each bag is detached at the separation line from the adjacent bags. By the action of pulling a bag, after the slot in the separation line in the remaining layers engages the tongue of a dispenser, the pulling force is transferred from the connected layers of the first bag to the remaining connected layer(s) of the next bag on the roll. The top layer transfers no force to the next bag because it is completely detached from the web at the separation line; likewise, the top layer of the next bag receives no force from the first bag because it is completely detached at the separation line. As a result, after separation of the first bag from the roll, the front of the next bag is automatically partially opened.
It is also possible to detach only the bottom layer, or both the top and bottom layers. In a star-sealed (eight layer) bag, when the top (first) and bottom (eighth) layers are detached, only six layers remain connected. This makes it easier to separate a bag from the roll since only six layers have to be torn and disconnected along the preparation line.
The invention also includes a method and apparatus for detaching one or both of the outer layers as a web of bags is fed from one location to another location. To accomplish this a friction member engages the outer layer of the web to be detached downstream of the weld between two bags of the web while the friction member is moving at a speed greater than the web travel speed. This detaches the engaged layer along the web separation line. In a web where the separation line is upstream of the weld, the friction member engages the outer layer and exerts a drag force or is moved in a direction opposite to that of web travel.